R/multiplot.R

In larmarange/JLutils: Collection of R functions

#' Multiple plot
#'
#' Renders multiple ggplot plots in one image
#'
#' @param ... ggplot objects (or grobs)
#' @param plotlist a list of ggplot objects
#' @param cols number of columns in layout
#' @param layout a matrix specifying the layout. if present, \code{cols} is ignored
#' @param heights a unit vector giving the relative height of each row (optional)
#' @param widths a unit vector giving the relative width of each row (optional)
#'
#' @note If the layout is something like \code{matrix(c(1,2,3,3), nrow=2, byrow=TRUE)},
#' then plot 1 will go in the upper left, 2 will go in the upper right, and 3 will go all
#' the way across the bottom.
#'
#' @references Adapted by Joseph Larmarange from Winston Chang, \emph{Cookbook for R},
#' \url{http://www.cookbook-r.com/Graphs/Multiple_graphs_on_one_page_(ggplot2)/}
#'
#' @examples
#' require(ggplot2)
#' p1 <- ggplot(mtcars, aes(wt, mpg)) +
#'   geom_point()
#' p2 <- ggplot(mtcars, aes(factor(cyl))) +
#'   geom_bar()
#' p3 <- ggplot(mtcars, aes(factor(cyl), mpg)) +
#'   geom_violin()
#' p4 <- ggplot(mtcars, aes(factor(cyl), mpg)) +
#'   geom_boxplot()
#'
#' multiplot(p1, p2, p3, p4)
#' multiplot(p1, p2, p3, p4, cols = 2)
#' multiplot(p1, p2, p3, layout = matrix(c(1, 2, 3, 3), nrow = 2))
#' multiplot(p1, p2, p3, layout = matrix(c(1, 2, 3, 3), nrow = 2, byrow = TRUE))
#' multiplot(p1, p2, p3, layout = matrix(c(1, 2, 3, 3), nrow = 2, byrow = TRUE), heights = c(3, 1))
#' @export

# Source: http://www.cookbook-r.com/Graphs/Multiple_graphs_on_one_page_(ggplot2)/

multiplot <- function(..., plotlist = NULL, cols = 1, layout = NULL, heights = NULL, widths = NULL) {
  if (!requireNamespace("gridExtra")) {
    stop("gridExtra package is required. Please install it.")
  }

  # Make a list from the ... arguments and plotlist
  plots <- c(list(...), plotlist)

  numPlots <- length(plots)

  # If layout is NULL, then use 'cols' to determine layout
  if (is.null(layout)) {
    # Make the panel
    # ncol: Number of columns of plots
    # nrow: Number of rows needed, calculated from # of cols
    layout <- matrix(seq(1, cols * ceiling(numPlots / cols)),
      ncol = cols, nrow = ceiling(numPlots / cols)
    )
  }

  gridExtra::grid.arrange(grobs = plots, newpage = TRUE, layout_matrix = layout, heights = heights, widths = widths)
}